1. Field of the Invention
The present invention relates to a steering wheel in which a portion of a core metal is covered with a wooden part, and to a method for manufacturing the same.
2. Description of the Related Art
A steering wheel used in a steering device of a vehicle, or the like, is provided with a core metal (a core grid) made of a metal having a ring-shaped rim portion, a boss portion formed at a central portion of the rim portion, and spoke portions for connecting the rim portion and the boss portion integrally. Further, outer coverings are usually attached at a portion of the rim portion and a portion of each spoke portion of the core metal for improving the touch when a driver holds the steering wheel. Some steering wheels employ woods for the outer coverings in order to meet various demands from users, such as matching the steering wheel with interior decoration of the vehicle.
Usually, when woods (wooden outer covers) are partly employed as the outer coverings, and the remaining portions, in which the wooden outer covers are not attached, are covered with synthetic resins such as urethane, the core metal is put in a metal mold for injection molding in a state in which the wooden outer covers, which have been shaped, painted, and the like, are attached at the rim portion. In this state, urethane resin is injected into the metal mold to cover the remaining portions in which the wooden outer covers are not attached with the urethane resin.
However, if the injection molding of the urethane resin is carried out in this manner, surfaces of the wooden outer covers are likely to contact and be scratched by the metal mold when the core metal is put in the metal mold. Therefore, in this case, workers have to pay close attention so as not to contact the wooden outer covers with the metal mold, and this makes the work inefficient.
In view of the aforementioned, objects of the present invention are to provide a steering wheel having partially applied wooden outer covers, which can be produced without having the wooden outer covers scratched, and the like, and can be produced with high working efficiency, as well as to provide a method for manufacturing the same.
A first aspect of the present invention is a method for manufacturing a steering wheel comprising steps of: attaching a wood member formed from a pure wooden material at a portion of a core metal which is formed in a ring shape; forming an outer covering core material from a synthetic resin material around a predetermined site of the core metal other than a portion at which the wood member is attached; shaping the wood member attached to the core metal after the outer covering core material is formed at the predetermined site.
A second aspect of the present invention is a method for manufacturing a steering wheel according to the first aspect further comprising a step of attaching a limiting member to the core metal at a portion between the wood material and the outer covering core material for limiting relative displacement of the wood member with respect to the outer covering core material along a circumferential direction of the core metal.
In the above-described method for manufacturing a steering wheel, first, the wood members formed from a pure wooden material of wood are attached at portions of the core metal which is formed in a ring shape in a step for attaching wood members. Then, in a step for forming core materials, the outer covering core materials are formed from synthetic resin material around predetermined sites of the core metal other than the portions thereof, at which the wood members are attached.
Further, after the step of forming the core materials, outline of the wood members are shaped in a step of shaping. Note that, since the wood members are shaped after the outer covering core materials are formed in this manufacturing method, even if the outer surfaces of the wood members are scratched when the outer covering core materials are formed, quality of appearance of the wood members in finished state is not degraded.
Moreover, in the second aspect, in a step of attaching the limiting members, the limiting members are attached to the core metal at portions thereof between the outer covering core materials and the shaped wood members, and the limiting members limit relative displacement of the wood members with respect to the outer covering core materials along the circumferential direction of the core metal. That is, since the wood members are shaped after the outer covering core materials are formed in this manufacturing method as described above, minimum spaces are required between the wood members and the outer covering core materials upon shaping the wood members. In this manufacturing method, the limiting members are attached to fill the spaces after the wood members are shaped, and therefore, appearance (of the steering wheel) is not degraded and, at the same time, displacement of the wood members can be limited.
A third aspect of the present invention is a method for manufacturing a steering wheel according to the second aspect further comprising a step of attaching a covering member for covering the outer covering core material and the limiting member from outside to the outer covering core material and the limiting member attached to the core metal.
In the above-described method for manufacturing a steering wheel, the covering portions are attached to both of the outer covering core materials and the limiting members so as to cover the outer covering core materials and the limiting members in the step of attaching covering portions. Thus, the outer covering core materials and the limiting members appear as if they are continuous (integral), and the limiting members are not seen from outside, thereby improving appearance (of the steering wheel).
A fourth aspect of the present invention is a steering wheel comprising: a core metal formed in a substantial ring shape; an outer covering core material for covering a portion of the core metal; a wood member formed from a pure wooden material, for covering the core metal at a side of the outer covering core material along a circumferential direction of the core metal; and a limiting member, which is placed between the outer covering core material and the wood member, for limiting relative displacement of the wood member with respect to the outer covering core material along the circumferential direction of the core metal.
In the steering wheel having the above-described structure, the limiting members are attached between the wood members and the outer covering core materials attached to the core metal, and the limiting members limit relative displacement of the wood members with respect to the outer covering core materials. A width, in the circumferential direction of the core metal, of the limiting member is determined on the basis of a space between the outer covering core material and the wood member which is needed in the shaping of the wood member. (Preferably, the width is the same as the space) That is, in a state before the limiting members are attached to the core metal, there are enough spaces for allowing displacement of the wood members with respect to the outer covering core materials. Presence of these spaces allows shaping, and the like, of the wood members after attachment (forming) of the outer covering core materials. Therefore, even if the outer surfaces of the wood members are scratched when the outer covering core materials are formed, and the like, since the wood member are shaped thereafter, quality of appearance of the steering wheel in a finished state is not degraded.
A fifth aspect of the present invention is the steering wheel according to the fourth aspect further comprising a covering member for covering the outer covering core material and the limiting member from outside.
In the steering wheel having the above-described structure, the limiting members and the outer covering core materials are covered with the covering members. Thus, the outer covering core materials and the limiting members appear as if they are continuous (integral), and the limiting members are not seen from outside, thereby improving appearance (of the steering wheel).
A sixth aspect of the present invention is the steering wheel according to the fourth aspect, wherein a cross section in an axial direction of the core metal of the limiting member is smaller than a cross section in the axial direction of the core metal of the wooden member.
A seventh aspect of the present invention is the steering wheel according to the fourth aspect, wherein the limiting member comprises an occupant side member and a counter occupant side member.
An eighth aspect of the present invention is the steering wheel according to the fourth aspect, wherein the limiting member is made of a single piece.
In the sixth aspect of the present invention, the cross section, in the axial direction of the core metal, of the limiting member is smaller than the cross section, in the axial direction of the core metal, of the wooden member. In the seventh aspect of the present invention, the limiting member comprises the occupant side member and the counter occupant side member.
To be more concrete, an occupant side surface of the occupant side member of the limiting member in the axial direction of the core metal is formed to be positioned at a counter-occupant side, along the axial direction of the core metal, from an occupant side surface of the wood member in the axial direction of the core metal. Further, a counter occupant side surface of the counter occupant side member of the limiting member in the axial direction of the core metal is formed to be positioned at an occupant side, along the axial direction of the core metal, from a counter occupant side surface of the wood member in the axial direction of the core metal.
Therefore, forming the covering member on the limiting member and the outer covering core material becomes easy, and by forming the covering member on the limiting member and the outer covering core material, the limiting member and the outer covering core material cannot be seen from outside. Therefore, appearance (of the steering wheel) is improved.
In the eighth aspect of the present invention, because the limiting member is made of a single piece, reduction of a number of parts can be archived.